In order to recover natural resources from subterranean formations it is often necessary to perform tasks related to exploration, monitoring, maintenance and construction in remote locations that are either difficult or impractical for personnel to reach directly. For example, boreholes may be drilled tens of thousands of meters into the earth, and in the case of offshore drilling, the borehole may be thousands of meters under water. One of the technical challenges to performing tasks in such remote locations is providing power to equipment. It is known to power downhole and undersea equipment via either stored energy or wireline connection to the surface. However, both of these techniques have disadvantages. For example, a wireline connection to the surface limits that distance at which the equipment can operate relative to the energy source, and may require a relatively significant portion of the limited volume of a borehole. Using stored energy avoids some of the disadvantages of a wireline connection to the surface, but relatively little energy can be stored in comparison to requirements because of size limitations. For example, the available volume in a borehole environment is small. Further, both wireline connection to the surface and stored energy techniques require the presence of operators, e.g., a surface vessel to either provide the wireline energy or recharge the energy storage means. Various techniques associated with energy production are described below.
U.S. Pat. No. 3,938,020 A, CHARGER CIRCUIT FOR ACCESSORY BATTERY, describes a charging circuit adapted to harvest excess energy from a resonating power circuit. Energy is inductively transferred from the power circuit to the charging circuit, thereby allowing the circuits to remain electrically isolated. The charging circuit utilizes gate controlled thyristors for coupling the harvested energy to a battery, and includes means for gating the thyristors at the proper time with respect to the resonant cycle in the power circuit.
U.S. Pat. No. 4,387,318, PIEZO-ELECTRIC FLUID ELECTRIC GENERATOR, describes a bending element that generates electrical power when deformed by fluid flow. The bending element is fixed to mounting means at one end and to a fin-like driving means at the other end.
U.S. Pat. No. 5,839,508, DOWNHOLE APPARATUS FOR GENERATING ELECTRICAL POWER IN A WELL, describes a power generating device which is attached to a side passageway of production tubing. An electrical generator in the side passageway is used to generate electrical energy using the fluid flow. A flow diverter is used to control the distribution of fluid flow between the main passageway of the production tubing and the side passageway.
U.S. Pat. No. 6,504,258 B2, VIBRATION BASED DOWNHOLE POWER GENERATOR, describes production tubing having integral power generating assemblies. The power generating assemblies are attached to a member of the production tubing that is caused to vibrate by fluid flow. The power generating assemblies may include magnet and coil arrangements or a piezoelectric material. The movement of the member is used to generate electrical energy.
U.S. Pat. No. 6,532,740 B1, GENERATOR EMPLOYING THE CORIOLIS EFFECT, describes a system for employing the Coriolis effect for the generation and storage of energy. The system includes a vortex chamber for rotational acceleration of superheated, supersaturated water vapor and heated air. A water intake assembly is adapted to deliver a directed flow of superheated water vapor to a lower portion of the vortex chamber while the air intake assembly is adapted to deliver a flow of heated air to the lower portion of the vortex chamber. The air intake assembly includes an electrical generator operable by airflow drawn from the air intake assembly.
U.S. Pat. No. 6,768,214, VIBRATION BASED POWER GENERATOR, describes a device with a member that is displaced in response to fluid flow. The displacement of the member is used to induce strain on a piezoelectric material, and thereby generate electricity.
U.S. Pat. No. 6,856,036 B2, INSTALLATION FOR HARVESTING KINETIC ENERGY OF OCEAN CURRENTS IN DEEPWATER, describes utilization of a semi-submersible platform and multiple, vertically oriented Darrieus-type hydraulic turbines with funnels. The turbines are located below sea level at a depth sufficient to isolate them from wave action. Electric power generators are located on a structure above water, and operate to provide electric power which is transmitted to the shore. One of the embodiments is designed to harvest energy from tidal currents in deepwater.
U.S. Pat. No. 7,116,036 B2, ENERGY HARVESTING SYSTEM, describes a device that collects acoustic energy and transforms it into electrical energy for use by a sensor.
US 20060133733 A1, POWER HARVESTING, describes a device having an electromagnetic (EM) radiation intensity modulator configured to receive EM radiation from at least one source and an energy converter for converting the EM radiation into electrical energy.
US 20060130476 A1, ENERGY SCAVENGERS WHICH ADJUST THEIR FREQUENCY BY ALTERING LIQUID DISTRIBUTIONS ON A BEAM, describes a system with a selectively configurable beam, the distribution of mass of which can be selectively altered by adjusting one or more characteristics. Specific strategies utilizing continuous electro-wetting and selective formation or movement of gases in liquid are disclosed. The selectively configurable beams are used in systems for harvesting vibrational energy from vibrating bodies.
US 20060063522 A, SELF-POWERING AUTOMATED BUILDING CONTROL COMPONENTS, describes a network of wireless radios for controlling operation of equipment, and locating assets and personnel. The wireless radios may be powered by energy generators that scavenge energy from the building, building equipment, or building environment. For example, the energy generators may utilize micro-electro-mechanical components or piezoelectric materials driven by vibrations. The energy generators may alternatively generate electrical energy from light, thermal, kinetic, radio frequency, movement or other forms of energy.
WO 2006093790 A2, WIND FIN: ARTICULATED, OSCILLATING WIND POWER GENERATOR, describes a system for harvesting the kinetic energy of a fluid flow for power generation by using an articulated airfoil capable of form inversion. Pivoted about a mast, the airfoil moves in an oscillatory manner in response to aerodynamic lift forces. The airfoil has a fixed configuration, and does not utilize mechanical trimming or aeroelastic flutter.
US 20060175937 A1, STRAIN ENERGY SHUTTLE APPARATUS AND METHOD FOR VIBRATION ENERGY HARVESTING, describes a device for low frequency vibration energy harvesting (VEH) with actuators requiring a low deflection force. The device includes a piezo flexure that is loaded with a compressive pre-load force to place the piezo flexure under compression. The compressive pre-load force flexes the piezo flexure into one of two stable positions, these positions being offset on opposite sides of a longitudinal centerline representing the position of the piezo flexure that would be produced without application of the compressive pre-load force. The compressive pre-load effectively provides a negative spring constant which “softens” the piezo flexure and enhances responsiveness to low frequency vibration energy.
GB1116451 A, METHOD OF AND APPARATUS FOR TRANSMITTING ENERGY BY PRESSURE OSCILLATIONS IN A FLUID, describes a fluid-pressure apparatus with a branch duct of a gas or liquid-filled duct through which oscillations are transmitted by a mechanical oscillator to a receiver which is connected to a cylinder having an adjustable piston.